http://forums.knowledgetree.org/viewtopic.php?f=6&t=20333
to fix this, open yum.conf
to do so,
CODE: SELECT ALL
#nano /etc/yum.conf


then add the following line
CODE: SELECT ALL
exclude=php-5.3*,mod-php-5.3*,zend-server-php-5.3*


the file will look like this:

[main]
cachedir=/var/cache/yum
keepcache=0
debuglevel=2
logfile=/var/log/yum.log
distroverpkg=redhat-release
tolerant=1
exactarch=1
obsoletes=1
gpgcheck=1
plugins=1
exclude=mod-php-5.3*,php-5.3*,zend-server-php-5.3*
# Note: yum-RHN-plugin doesn't honor this.
metadata_expire=1h

installonly_limit = 5

# PUT YOUR REPOS HERE OR IN separate files named file.repo
# in /etc/yum.repos.d


this will let you run the installation, ill update if there was a problem after it.

http://wiki.knowledgetree.org/KnowledgeTree_3.7_-_Linux_Stack_Installation

KnowledgeTree 3.7 - Linux Stack Installation
Pre-installation steps

This step is required on Red Hat Enterprise Linux servers running with SELinux enabled.
Temporarily disable SELinux:
$ su - $ setenforce permissive

Automatic Installation Instructions

The following steps must be run as the root user.
1) Download the KnowledgeTree install script. (Available here)
2) Unpack the install script.
$ tar -xzf kt-linux-universal-installer-3.7.x.x.tgz
3) Set execute permissions on the install script.
$ cd knowledgetree-linux-universal-installer-3.7.x.x/ $ chmod +x knowledgetree-commercial.sh
4) Run the script.
$ sudo ./knowledgetree-commercial.sh
(Click here for information about what the KnowledgeTree Universal Install Script does.)
5) Confirm that you want to install KnowledgeTree.
6) Allow the install script to configure the required repositories and download all packages.
7) Enter your MySQL root password when prompted.


8) Start MySQL.
This step is only required on Red Hat Enterprise Linux
